The present invention relates to a unit for preventing nozzle blockage in an ink jet system printer and, more particularly, to a capping mechanism for covering a nozzle unit in an ink jet system printer of the ink-on-demand type.
An ink jet system printer of the ink-on-demand type includes an orifice which is exposed to ambient conditions via a nozzle slit. When the ink jet system printer is placed in the non-operating condition for a long period, there is a possibility that the ink liquid present in the nozzle slit will solidify and block the orifice.
To prevent the above-mentioned blocking of the orifice, a capping mechanism has been proposed to cover the nozzle slit while the ink jet system printer is placed in a non-operating condition. However, the conventional capping mechanism includes a solenoid which makes the system complicated and large.
Accordingly, an object of the present invention is to provide a simplified capping mechanism for covering a nozzle orifice in an ink jet system printer when the ink jet system printer is placed in a non-operating condition.
Another object of the present invention is to provide a system for preventing nozzle blockage in an ink jet system printer of the ink-on-demand type.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a cap shift mechanism is provided for shifting a cap toward a printer head when the printer head is located in a stand-by position, thereby covering the nozzle slit with the cap when the ink jet system printer is placed in a non-operating condition. The cap shift mechanism does not include an energized drive system. The cap shift mechanism is correlated with the movement of the printer head so that the cap is automatically shifted when the printer head is moved to the stand-by position.
In a preferred form, a first spring means is provided for smoothly shifting the cap toward the printer head when the printer head is located in the stand-by position. A second spring means is provided for tightly depressing the cap against the printer head when the printer head is located in the stand-by position such that the actual printing operation is not conducted.